Study Evaluates Alzheimer’s Blood Biomarker Across Racial and Ethnic Groups

Alzheimer’s disease trials increasingly depend on identifying cognitively unimpaired people who already have elevated brain amyloid. Blood biomarkers may help reduce reliance on positron emission tomography scans during early screening, but their performance across racial and ethnic groups remains an important diagnostic question. Historically underrepresented populations have also been less represented in Alzheimer’s clinical trials. 

The Keck School of Medicine of USC (Los Angeles, CA, USA) evaluated %p-tau217, a blood biomarker that measures the proportion of a tau protein fragment carrying an Alzheimer’s-related modification. The test is used to identify individuals more likely to have elevated brain amyloid, with confirmation performed by positron emission tomography (PET). The findings support its use as an initial screening tool in a preclinical Alzheimer’s disease trial.

Image: The test identifies individuals more likely to have elevated brain amyloid, with PET used for confirmation (Image Credit: Adobe Stock)

The study included 15,612 cognitively unimpaired adults ages 55 to 80. Data were collected at 106 research sites across Asia, Australia, Europe, and North America during screening for the AHEAD 3-45 trials, which are testing lecanemab in people with certain levels of brain amyloid but no symptoms of Alzheimer’s disease. Participants first underwent blood-based screening, and eligible individuals proceeded to additional assessments, including PET scans.

Although %p-tau217 levels differed across racial and ethnic groups, the relationship between the biomarker and Alzheimer’s-related measures was generally consistent across racial groups. Higher %p-tau217 levels were consistently associated with higher brain amyloid levels measured by PET. Biomarker levels were generally lower among Asian and Black participants than among white participants, and lower among Hispanic participants than among non-Hispanic participants. Carriers of the APOE ε4 variant generally had higher %p-tau217 levels than adults without the variant, a pattern that largely held across racial and ethnic groups.

The findings were published in JAMA Neurology in 2026. The Alzheimer’s Plasma Extension Study, or APEX, is following individuals who underwent AHEAD 3-45 screening but did not meet amyloid eligibility criteria. That study is continuing to collect blood tests, PET scans, and cognition measures to assess changes over time.

“We found that %p-tau217 levels were lower in populations that have historically been underrepresented in clinical trials. Importantly, however, the relationship between the biomarker and brain amyloid was generally consistent across racial groups. This supports the use of blood-based biomarkers as an initial screening tool for elevated amyloid in a preclinical Alzheimer's disease trial,” said Doris P. Molina-Henry, Ph.D., the study's corresponding author and associate professor of research neurology with the Epstein Family Alzheimer's Therapeutic Research Institute at the Keck School of Medicine of USC.

“Following these individuals over time will help us understand how Alzheimer's-related biomarkers change and how those changes relate to brain amyloid and cognition,”added Molina-Henry.

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Keck School of Medicine of USC